1. Field
One or more embodiments of the present invention relate to a positive electrode material for a lithium battery, a positive electrode prepared from the positive electrode material, and a lithium battery including the positive electrode.
2. Description of the Related Art
Secondary lithium batteries produce electric energy due to oxidation and reduction reactions occurring when lithium ions are intercalated into or deintercalated from a positive electrode and a negative electrode. Each of the positive and negative electrodes includes an active material that enables the intercalation and deintercalation of the lithium ions. An organic electrolytic solution or a polymer electrolytic solution is positioned between the positive electrode and the negative electrode.
As a positive active material for a secondary lithium battery, for example, an oxide that has a structure that enables the intercalation of lithium ions and includes lithium and a transition metal may be used. Examples of the oxide are lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and lithium nickel cobalt manganese oxide (Li[NiCoMn]O2, Li[Ni1-x-yCoxMny]O2).
If a positive electrode plate includes a positive active material for a secondary lithium battery and an aqueous binder, alkali metal ions in the positive active material that do not react or that are dissolved in water may contribute to a substantial increase in the pH of the prepared positive active material slurry. Thus, the positive active material slurry is strongly basic.
When the aqueous positive active material slurry is coated on an aluminum electrode substrate, however, due to its high pH, the aluminum electrode substrate corrodes, generating H2 gas, and many pin holes are formed on the electrode plate, thereby increasing the internal resistance of the positive electrode plate.